UPD78F9500MA-CAC-A Datasheet, PDF (324/342 Pages) Renesas Technology Corp – 8-Bit Single-Chip Microcontrollers

APPENDIX D LIST OF CAUTIONS
This appendix lists cautions described in this document.
“Classification (hard/soft)” in table is as follows.
Hard: Cautions for microcontroller internal/external hardware
Soft: Cautions for software such as register settings or programs
Function
Details of
Function
Cautions
(1/15)
Page
Pin
functions
Memory
space
Port
functions
P22/X2/ANI2,
P23/X1/ANI3
(μPD78F920x)
P22,
P23/EXCLK,
P34/RESET
(μPD78F950x)
SP: stack
pointer
P22/X2/ANI2,
P23/X1/ANI3
(μPD78F920x)
P22,
P23/EXCLK,
P34/RESET
(μPD78F950x)
P34
(μPD78F920x)
P34
(μPD78F950x)
The P22/X2/ANI2, P23/X1/ANI3 pins are pulled down during reset.
The P22 and P23/EXCLK pins are pulled down during reset. The P34/RESET
pin is pulled up during reset by the reset pin function/power-on clear circuit.
Since reset signal generation makes the SP contents undefined, be sure to
initialize the SP before using the stack memory.
Stack pointers can be set only to the high-speed RAM area, and only the lower
10 bits can be actually set.
0FF00H is in the SFR area, not the high-speed RAM area, so it was converted
to 0FB00H that is in the high-speed RAM area. When the value is actually
pushed onto the stack, 1 is subtracted from 0FB00H to become 0FAFFH, but
that value is not in the high-speed RAM area, so it is converted to 0FEFFH,
which is the same value as when 0FF00H is set to the stack pointer.
The P22/X2/ANI2, P23/X1/ANI3 pins are pulled down during reset.
The P22 and P23/EXCLK pins are pulled down during reset. The P34/RESET
pin is pulled up during reset by the reset pin function/power-on clear circuit.
Because the P34 pin functions alternately as the RESET pin, if it is used as an
input port pin, the function to input an external reset signal to the RESET pin
cannot be used. The function of the port is selected by the option byte. For
details, refer to CHAPTER 15 OPTION BYTE.
Also, since the option byte is referenced after the reset release, if low level is
input to the RESET pin before the referencing, then the reset state is not
released. When it is used as an input port pin, connect the pull-up resistor.
Because the P34 pin functions alternately as the RESET pin, if it is used as an
input port pin, the function to input an external reset signal to the RESET pin
cannot be used. The function of the port is selected by the option byte. For
details, refer to CHAPTER 15 OPTION BYTE.
Also, since the option byte is referenced after the reset release, if low level is
input to the RESET pin before the referencing, then the reset state is not
released. When it is used as an input port pin, connect an on-chip pull-up
resistor by using bit 4 (PU34) of pull-up resistor option register 3 (PU3).
pp. 21,
22, 24, 25
pp. 23
24, 25, 26
p. 38
p. 38
p. 54
p. 55
p. 65
p. 65
322
User’s Manual U18172EJ3V0UD